Flow device for exhaust treatment system

ABSTRACT

An exhaust treatment system includes an exhaust conduit for conveying exhaust gases from an engine of a vehicle. An aftertreatment device is disposed in the exhaust conduit. A flow device is disposed upstream of the aftertreatment device. The flow device includes a base having a first surface and an oppositely disposed second surface. The base defines a plurality of openings. A plurality of flow deflectors is engaged to the base at the plurality of openings. Each flow deflector includes a first deflector that extends outwardly from the first surface of the base and a second deflector that extends outwardly from the second surface of the base. The first and second deflectors define a passage. Flow of exhaust gases through the passage cause exhaust gases to swirl about a longitudinal axis of the exhaust conduit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 12/846,252,filed Jul. 29, 2010, now U.S. Pat. No. 8,539,761, which claims thebenefit of provisional application Ser. No. 61/294,391, filed Jan. 12,2010, which applications are incorporated herein by reference in theirentireties.

BACKGROUND

Vehicles equipped with diesel engines typically include exhaust systemsthat have aftertreatment components such as selective catalyticreduction catalyst devices, lean NOx catalyst devices, or lean NOx trapdevices to reduce the amount of undesirable gases, such as nitrogenoxides (NOx) in the exhaust. In order for these types of aftertreatmentdevices to work properly, a doser injects reactants, such as urea,ammonia, or hydrocarbons, into the exhaust gas. As the exhaust gas andreactants flow through the aftertreatment device, the exhaust gas andreactants convert the undesirable gases, such as NOx, into moreacceptable gases, such as nitrogen and oxygen. However, the efficiencyof the aftertreatment system depends upon how evenly the reactants aremixed with the exhaust gases. Therefore, there is a need for a flowdevice that provides a uniform mixture of exhaust gases and reactants.

SUMMARY

An aspect of the present disclosure relates to an exhaust treatmentsystem. The exhaust treatment system includes an exhaust conduit forconveying exhaust gases from an engine of a vehicle. An aftertreatmentdevice is disposed in the exhaust conduit. A flow device is disposedupstream of the aftertreatment device. The flow device includes a basehaving a first surface and an oppositely disposed second surface. Thebase defines a plurality of openings. A plurality of flow deflectors isengaged to the base at the plurality of openings. Each flow deflectorincludes a first deflector that extends outwardly from the first surfaceof the base and a second deflector that extends outwardly from thesecond surface of the base. The first and second deflectors define apassage. Flow of exhaust gases through the passage cause exhaust gasesto swirl about a longitudinal axis of the exhaust conduit.

Another aspect of the present disclosure relates to a flow device. Theflow device includes a base having a first surface and an oppositelydisposed second surface. The base defines a plurality of openings. Aplurality of flow deflectors is engaged to the base at the plurality ofopenings. Each flow deflector includes a first deflector that extendsoutwardly from the first surface of the base and a second deflector thatextends outwardly from the second surface of the base. The first andsecond deflectors define a passage. Flow of exhaust gases through thepassage cause exhaust gases to swirl about a central axis of the base.

A variety of additional aspects will be set forth in the descriptionthat follows. These aspects can relate to individual features and tocombinations of features. It is to be understood that both the foregoinggeneral description and the following detailed description are exemplaryand explanatory only and are not restrictive of the broad concepts uponwhich the embodiments disclosed herein are based.

DRAWINGS

FIG. 1 is a schematic representation of an engine exhaust system havingexemplary features of aspects in accordance with the principles of thepresent disclosure.

FIG. 2 is a fragmentary perspective view of an exhaust treatment systemsuitable for use in the engine exhaust system of FIG. 1.

FIG. 3 is a perspective view of a flow device suitable for use in theexhaust treatment system of FIG. 2.

FIG. 4 is a front view of the flow device of FIG. 3.

FIG. 5 is a side view of the flow device of FIG. 3.

FIG. 6 is a fragmentary cross-sectional view of the flow device taken online 6-6 of FIG. 4.

FIG. 7 is a fragmentary cross-sectional view of the flow device taken online 7-7 of FIG. 6.

FIG. 8 is a perspective view of an alternate embodiment of the flowdevice.

FIG. 9 is a front view of the flow device of FIG. 8.

FIG. 10 is a front view of a baffle suitable for use with the exhausttreatment system of FIG. 2.

FIG. 11 is a cross-sectional view of the baffle of FIG. 10.

DETAILED DESCRIPTION

Reference will now be made in detail to the exemplary aspects of thepresent disclosure that are illustrated in the accompanying drawings.Wherever possible, the same reference numbers will be used throughoutthe drawings to refer to the same or like structure.

Referring now to FIG. 1, an engine exhaust system, generally designated10, is shown. The engine exhaust system 10 includes an engine 12, a fueltank 14 for supplying fuel (e.g., diesel fuel) to the engine 12, an airintake 16, an air filter 18, and an exhaust conduit 20 for conveyingexhaust gas away from the engine 12. The engine exhaust system 10 alsoincludes an exhaust treatment system, generally designated 22, which isin communication with the exhaust conduit 20. In the subject embodiment,the exhaust treatment system 22 includes a doser 24, a flow device,generally designated 26, a baffle or a diameter restriction 28, and anaftertreatment device, generally designated 30.

The aftertreatment device 30 can include a structure such as a catalyticconverter, diesel particulate filter, a selective catalytic reduction(SCR) catalyst device, a lean NOx catalyst device, a lean NOx trap, orother device for removing pollutants from the exhaust stream. As thesetypes of aftertreatment devices 30 are well known to those skilled inthe art, the aftertreatment devices 30 will only be briefly describedherein.

Catalytic converters (diesel oxidation catalysts or DOC's) are typicallyused in an exhaust system to convert undesirable gases such as carbonmonoxide and hydrocarbons from a vehicle's exhaust into carbon dioxideand water. DOC's can have a variety of known configurations. Exemplaryconfigurations include substrates defining channels that extendcompletely therethrough. Exemplary catalytic converter configurationshaving both corrugated metal and porous ceramic substrates/cores aredescribed in U.S. Pat. No. 5,355,973, which is hereby incorporated byreference in its entirety. The substrates preferably include a catalyst.For example, the substrate can be made of a catalyst, impregnated with acatalyst or coated with a catalyst. Exemplary catalysts include preciousmetals such as platinum, palladium and rhodium, and other types ofcomponents such as base metals or zeolites.

In one non-limiting embodiment, a catalytic converter can have a celldensity of at least 200 cells per square inch, or in the range of200-400 cells per square inch. A preferred catalyst for a catalyticconverter is platinum with a loading level greater than 30 grams/cubicfoot of substrate. In other embodiments the precious metal loading levelis in the range of 30-100 grams/cubic foot of substrate. In certainembodiments, the catalytic converter can be sized such that in use, thecatalytic converter has a space velocity (volumetric flow rate throughthe DOC/volume of DOC) less than 150,000/hour or in the range of50,000-150,000/hour.

The diesel particulate filter (DPF), on the other hand, is typicallyused in an exhaust system to remove particulate matter (e.g., carbonbased particulate matter such as soot) from the exhaust. DPF's can havea variety of known configurations. An exemplary configuration includes amonolith ceramic substrate having a “honey-comb” configuration ofplugged passages as described in U.S. Pat. No. 4,851,015, which ishereby incorporated by reference in its entirety. Wire meshconfigurations can also be used. In certain embodiments, the substratecan include a catalyst. Exemplary catalysts include precious metals suchas platinum, palladium and rhodium, and other types of components suchas base metals or zeolites.

For certain embodiments, diesel particulate filters can have aparticulate mass reduction efficiency greater than 75%. In otherembodiments, diesel particulate filters can have a particulate massreduction efficiency greater than 85%. In still other embodiments,diesel particulate filters can have a particulate mass reductionefficiency equal to or greater than 90%. For purposes of thisspecification, the particulate mass reduction efficiency is determinedby subtracting the particulate mass that enters the diesel particulatefilter from the particulate mass that exits the diesel particulatefilter, and by dividing the difference by the particulate mass thatenters the diesel particulate filter.

The selective catalytic reduction (SCR) catalyst device is typicallyused in an exhaust system to remove undesirable gases such as nitrogenoxides (NOx) from the vehicle's emissions. SCR's are capable ofconverting NOx to nitrogen and oxygen in an oxygen rich environment withthe assistance of reactants such as urea or ammonia, which are injectedinto the exhaust stream upstream of the SCR through the doser 24.

The lean NOx catalyst device is also capable of converting NOx tonitrogen and oxygen. In contrast to SCR's, lean NOx catalysts usehydrocarbons as reducing agents/reactants for conversion of NOx tonitrogen and oxygen. The hydrocarbon is injected into the exhaust streamupstream of the lean NOx catalyst. At the lean NOx catalyst, the NOxreacts with the injected hydrocarbons with the assistance of a catalystto reduce the NOx to nitrogen and oxygen. While the exhaust treatmentsystem 22 will be described as including an SCR, it will be understoodthat the scope of the present disclosure is not limited to an SCR asthere are various catalyst devices that can be used in accordance withthe principles of the present disclosure.

The lean NOx traps use a material such as barium oxide to absorb NOxduring lean burn operating conditions. During fuel rich operations, theNOx is desorbed and converted to nitrogen and oxygen by reaction withhydrocarbons in the presence of catalysts (precious metals) within thetraps.

Referring now to FIGS. 1 and 2, in the subject embodiment, the exhausttreatment system 22 includes a housing assembly, generally designated32, having a first axial end 34 and an oppositely disposed second axialend 36. In the depicted embodiment of FIG. 2, a portion of the housingassembly 32 is a double walled structure having an inner wall 38 and anouter wall 40.

In the subject embodiment, the first axial end 34 includes an inlet 42.In one embodiment, the inlet 42 is generally aligned with the exhaustconduit 20. In another embodiment, the inlet 42 is disposed in asidewall adjacent to the first axial end 34. The second axial end 36 ofthe housing assembly 32 includes an outlet 44. In the subjectembodiment, the flow device 26, which will be described in greaterdetail subsequently, is disposed within the housing assembly 32 andpositioned adjacent to the inlet 42. The aftertreatment device 30 isdisposed within the housing assembly 32 and positioned between the flowdevice 26 and the outlet 44. The baffle 28 is disposed within thehousing assembly 32 and positioned downstream of the flow device 26 suchthat the baffle 28 is located between the flow device 26 and theaftertreatment device 30.

Referring now to FIGS. 1-7, the flow device 26 will be described. Theflow device 26 is adapted to receive exhaust gases in a generally axialdirection and to redirect the exhaust gases so that at least a portionof the exhaust gases swirl about a longitudinal axis 45 of the housingassembly 32. In the subject embodiment, the flow device 26 includes abody 46 having a base 48 and a plurality of flow deflectors 50.

In the depicted embodiment, the base 48 is generally planar in shape.The base 48 includes a first surface 52 and an oppositely disposedsecond surface 54. The first surface 52 faces in a direction toward theaftertreatment device 30 while the second surface 54 faces in adirection toward the inlet 42 of the housing assembly 32.

The body 46 further includes a plurality of outer edge portions 56disposed at a periphery 58 of the base 48. The outer edge portions 56extend outwardly from the base 48 in a direction that is generallyperpendicular to the first surface 52. In the depicted embodiment, thereare four outer edge portions 56.

The outer edge portions 56 are separated by notches 60. In the depictedembodiment, the notches 60 are arcuate in shape and are disposed at theperiphery 58 of the base 48. The notches 60 extend through the first andsecond surfaces 52, 54 of the base 48. The outer edge portions 56 andthe notches 60 are alternately disposed about the periphery 58 of thebase 48 in a symmetrical configuration. In the subject embodiment, thereare four outer edge portions 56 and four notches 60. Each of the fournotches 60 is disposed 90° from an adjacent notch 60.

In the depicted embodiment, the body 46 is generally circular in shape.The outer edge portions 56 define a diameter D that is sized so thatwhen the body 46 is disposed in the housing assembly 32, the outer edgeportions 56 of the body 46 substantially block the flow of exhaustbetween the outer edge portions 56 and the housing assembly 32. Whilethe outer edge portions 56 block the flow of exhaust between the outeredge portions 56 and the housing assembly 32, the notches 60 are sizedto allow some exhaust to flow axially through the notches 60. In thesubject embodiment, the outer edge portions 56 of the body 46 aremounted (e.g., spot welded, etc.) to an inner diameter of the housingassembly 32.

Referring now to FIGS. 3-7, the flow deflectors 50 will be described. Inthe depicted embodiment, the body 46 includes a first plurality of flowdeflectors 50 a and a second plurality of flow deflectors 50 b. In thedepicted embodiment, each of the first and second pluralities of flowdeflectors 50 a, 50 b are symmetrically arranged about a central axis 62that extends through a center of the base 48 of the body 46. Each of theflow deflectors 50 of the first plurality of flow deflectors 50 a isdisposed a first radial distance R₁ from the central axis 62 while eachof the flow deflectors 50 of the second plurality of flow deflectors 50b is disposed a second radial distance R₂ from the central axis 62. Inthe depicted embodiment, the second radial distance R₂ is less than thefirst radial distance R₁.

In the depicted embodiment, the flow deflectors 50 of the firstplurality of flow deflectors 50 a are disposed between adjacent notches60. In the depicted embodiment, the first plurality of flow deflectors50 a includes four flow deflectors 50. The flow deflectors 50 of thefirst plurality of flow deflectors 50 a are disposed at 45° from theadjacent notches 60.

In the depicted embodiment, the flow deflectors 50 of the secondplurality of flow deflectors 50 b are generally aligned with the notches60. In the depicted embodiment, the second plurality of flow deflectors50 b includes four flow deflectors 50.

Each of the flow deflectors 50 includes an opening 64 that extendsthrough the first and second surfaces 52, 54 of the base 48. In thedepicted embodiment, the opening 64 is generally oval in shape whenviewed in a direction that is generally perpendicular to the base 48 andincludes a major axis and a minor axis. The major axis is greater thanthe minor axis.

Each of the flow deflectors 50 further includes a first deflector 66 anda second deflector 68. The first deflector 66 extends outwardly from thefirst surface 52 while the second deflector 68 extends outwardly fromthe second surface 54. In the depicted embodiment, each of the first andsecond deflectors 66, 68 is curved so that each of the first and seconddeflectors 66, 68 is generally scoop shaped.

Each of the first and second deflectors 66, 68 includes a perimeter 70having a first portion 72 and a second portion 74. The first portion 72of the perimeter 70 of each of the first and second deflectors 66, 68extends around a portion of the opening 64. The first portion 72 of thefirst deflector 66 is engaged to the first surface 52 of the base 48 atthe opening 64 while the first portion 72 of the second deflector 68 isengaged to the second surface 54 of the base 48 at the opening 64. Inthe depicted embodiment, the first portion 72 of the perimeter 70 ofeach of the first and second deflectors 66, 68 is monolithic with thebase 48 at the opening 64.

The second portion 74 of the perimeter 70 of each of the first andsecond deflectors 66, 68 extends across the opening 64. The secondportion 74 of the perimeter 70 of each of the first and seconddeflectors 66, 68 is disposed outwardly from the base 48. The secondportion 74 of the perimeter 70 of the first deflector 66 extendsoutwardly from the first surface 52 while the second portion 74 of theperimeter 70 of the second deflector extends outwardly from the secondsurface 54. In the depicted embodiment, a central location 76 (shown inFIG. 6) along the second portion 74 of the perimeter 70 of each of thefirst and second deflectors 66, 68 is the farthest extending locationalong the second portion 74 from the base 48 so that the second portion74 is generally parabolic in shape.

The first and second deflectors 66, 68 are oppositely arranged about theopening 64. The second portion 74 of the perimeter 70 of the firstdeflector 66 faces a first direction while the second portion 74 of theperimeter 70 of the second deflector 68 faces a second direction that isopposite from the first direction.

Referring now to FIG. 7, the first and second deflectors 66, 68 define apassage 78 through the base 48 of the flow device 26. A centrallongitudinal axis 80 extends through the center of the passage 78. Thecentral longitudinal axis 80 is disposed at an angle α with respect tothe base 48 of the flow device 26. In one embodiment, the angle α isless than 90°. In another embodiment, the angle α is in the range ofabout 15° to about 75°. In another embodiment, the angle α is in therange of about 30° to about 60°. In another embodiment, the angle α isless than or equal to about 45°. It will be understood that the angle αof the present disclosure is measured in accordance with the referencesymbol “α” as shown in FIG. 7.

Referring now to FIGS. 3 and 4, the base 48 of the flow device 26defines a central opening 82. The central opening 82 extends through thefirst and second surfaces 52, 54 of the base 48. An inner radius R₃ ofthe central opening is less than the second radial distance R₂ of thesecond plurality of flow deflectors 50 b. The central opening 82 allowsa portion of the exhaust gases to flow axially through the flow device26 which may reduce backpressure.

Referring now to FIGS. 8 and 9, an alternate embodiment of a flow device26′ is shown. The flow device 26′ is structurally similar to the flowdevice 26 described above. However, in the depicted embodiment of FIGS.8 and 9, a base 48′ of the flow device 26′ does not include the centralopening 82.

Referring now to FIGS. 10 and 11, the baffle 28 is shown. The baffle 28includes a body 90.

In the depicted embodiment, the body 90 includes an outer rim portion 92and a diameter restriction portion 94. The outer rim portion 92 isadapted for engagement (e.g., interference-fit, press-fit, weld, spotweld, adhere, etc.) with the housing assembly 32. In the depictedembodiment, the outer rim portion 92 is generally parallel to a centralaxis 95 that extends through the center of the body 90. The outer rimportion 92 includes an outer diameter D₁.

The diameter restriction portion 94 includes a first surface 96 and anoppositely disposed second surface 97. The first surface 96 is generallyconcave. In the depicted embodiment, the diameter restriction portion 94is generally frusto-spherical in shape. In an alternate embodiment, thediameter restriction portion 94 is generally frusto-conical in shape. Inthe depicted embodiment of FIG. 2, the first surface 96 of the baffle 28faces toward the first surface 52 of the flow device 26.

The diameter restriction portion 94 defines a central opening 98 thatextends through the body 90 and defines an inner diameter D₂. The innerdiameter D₂ of the central opening 98 is less than the outer diameter D₁of the outer rim portion 92 so that the central opening 98 is less thanthe inner diameter of the exhaust conduit 20.

The diameter restriction portion 94 further defines a plurality ofopenings 100 disposed about the central axis 96 so that the plurality ofopenings 100 is disposed between the inner diameter D₂ of the diameterrestriction portion 94 and the outer diameter D₁ of the outer rimportion 92. The plurality of openings 100 is symmetrically disposedabout the central axis 95. In the subject embodiment, the plurality ofopenings 100 includes eight openings.

Referring now to FIG. 1, the doser 24 will be described. The doser 24injects reactants (e.g., urea, ammonia, hydrocarbons) into the exhaustgases. The reductants in the exhaust gases help the aftertreatmentdevice 30 in converting the NOx to nitrogen and oxygen. In the depictedembodiment of FIG. 1, the doser 24 is disposed upstream of the fluiddevice 26 in the depicted embodiment. By injecting the reactants intothe exhaust gases at a location upstream from the flow device 26, thereactants from the doser 24 are subjected to the circumferentialswirling of the exhaust for a greater axial distance thereby resultingin a more uniform mixture of exhaust gases and reductants.

Referring now to FIGS. 1-7, the flow of exhaust gases through theexhaust treatment system 22 will be described. Exhaust enters thehousing assembly 32. The exhaust gases enter the flow device 26. Aportion of the exhaust gases flow axially through the notches 60.Another portion of the exhaust gases flow through the passages 78 of theflow deflectors 50. As the exhaust gases flow through passages 78, theflow direction of the exhaust gases change from a generally axialdirection to a direction that swirls about the longitudinal axis 45 ofthe housing assembly 32. The doser 24, in the subject embodiment,injects reactants (e.g., urea, ammonia, hydrocarbons) into the exhaustgases forming an exhaust mixture.

Due to the swirling of the exhaust gases, the reactants are uniformlydistributed in the exhaust. Uniform distribution of the reactants isimportant for the aftertreatment device 30 to perform effectively. Inthe prior art exhaust treatment systems, uniform distribution of thedoser contents into the exhaust gases was achieved through a long axialdistance between the doser and the aftertreatment device. However, bychanging the flow direction of the exhaust gases, the exhaust gases andthe contents of the doser that are injected into the exhaust gases areeffectively mixed over a much smaller axial distance. Therefore, oneadvantage of the present disclosure is that it provides a uniformmixture of the exhaust and the contents of the doser 24 over a smallaxial distance. Additionally, the swirling action allows reactants tovaporize and/or hydrolyze in a relatively short axial distance. Forexample, a reactant such as urea can be vaporized and decomposed intoammonia and carbon dioxide while swirling thereby shortening the axialdistance required for the vaporization and decomposition of the urea tooccur.

The exhaust mixture exits the flow device 26 and flows through thecentral opening 98 of the diameter restriction portion 94 of the baffle28. As the exhaust mixture swirls in the housing assembly 32, heavierreactants (e.g., unvaporized or unhydrolyzed reactants) in the exhaustmixture are pushed radially outward from the exhaust mixture bycentrifugal force such that the heavier reactants are retained against awall of the housing assembly 32. As the exhaust mixturecircumferentially flows past the reactants disposed against the wall ofthe housing assembly 32, these reactants are vaporized or hydrolyzed.After the vaporization or hydrolyzation of these reactants, thereactants reenter the exhaust mixture and pass through the centralopening 98 of the plurality of openings 96 in the baffle 28. After theexhaust mixture passes through the baffle 28, the exhaust mixture entersthe aftertreatment device 30.

By retaining the unvaporized or unhydrolyzed reactants at the baffle 28,the baffle 28 eliminates or reduces the amount of unvaporized orunhydrolyzed reactants in the exhaust mixture at the aftertreatmentdevice 30. Since the efficiency of the exhaust treatment system 22increases as the amount of unvaporized or unhydrolyzed reactants in theexhaust mixture decreases, the combination of the flow device 26 and thebaffle 28 allows for a more efficient exhaust treatment system 22 in amore compact space.

Various modifications and alterations of this disclosure will becomeapparent to those skilled in the art without departing from the scopeand spirit of this disclosure, and it should be understood that thescope of this disclosure is not to be unduly limited to the illustrativeembodiments set forth herein.

What is claimed is:
 1. An exhaust conduit adapted to cause exhaust gases to swirl about a longitudinal axis of the exhaust conduit when the exhaust gases flow through the exhaust conduit, the exhaust conduit comprising: a wall having a first side and an oppositely disposed second side, the wall defining a central flow passage extending through the wall, wherein the central flow passage is centered about the longitudinal axis of the exhaust conduit; and a plurality of flow deflecting passages extending through the wall, the plurality of flow deflecting passages being positioned around the central flow passage, the plurality of flow deflecting passages including a first set disposed at a first radial distance from the longitudinal axis and a second set disposed at a second radial distance from the longitudinal axis, and wherein the second radial distance is less than the first radial distance, the flow deflecting passages each including: a hole in the wall, the hole defining a perimeter; a first flow deflecting member extending from the first side of the wall, the first flow deflecting member joined to the wall at a first portion of the perimeter; and a second flow deflecting member extending from the second side of the wall, the second flow deflecting member joined to the wall at a second portion of the perimeter.
 2. The exhaust conduit of claim 1, wherein the wall includes a plate and the holes of the plurality of flow deflecting passages are included in the plate.
 3. The exhaust conduit of claim 2, wherein the holes of the plurality of flow deflecting passages are formed holes, wherein a first portion of material from each of the formed holes is included in a corresponding one of the first flow deflecting members, and wherein a second portion of material from each of the formed holes is included in a corresponding one of the second flow deflecting members.
 4. The exhaust conduit of claim 3, wherein the first flow deflecting members and the second flow deflecting members are formed scoop-shaped deflecting members.
 5. The exhaust conduit of claim 2, wherein the plate defines a plurality of notches disposed at a periphery of the plate, the notches extending through the first side and the second side of the wall.
 6. The exhaust conduit of claim 1, wherein the first flow deflecting member and the second flow deflecting member of a corresponding one of the flow deflecting passages define a passage axis and at least partially face each other about the passage axis.
 7. The exhaust conduit of claim 6, wherein the passage axis is disposed at an angle α with respect to the first side of the wall, the angle α being in a range of 30 degrees to 60 degrees.
 8. The exhaust conduit of claim 1, wherein the wall includes a flow blocking portion adapted to block flow of the exhaust gases parallel to the longitudinal axis of the exhaust conduit through the flow blocking portion.
 9. The exhaust conduit of claim 1, wherein each of the first and the second flow deflecting members includes compound curvature.
 10. A flow device comprising: a plate having a first side and an oppositely disposed second side; a first plurality of flow deflectors formed from the plate, the first plurality of flow deflectors extending outwardly from the first side of the plate; a second plurality of flow deflectors formed from the plate, the second plurality of flow deflectors extending outwardly from the second side of the plate; each of the first plurality of flow deflectors corresponding to one of the second plurality of flow deflectors to form a pair, wherein a first set of the flow deflector pairs is disposed at a first radial spacing from a center of the plate and a second set of the flow deflector pairs is disposed at a second radial spacing from the center of the plate, the second radial spacing being different from the first radial spacing; a plurality of holes in the plate, each of the holes corresponding to one of the flow deflector pairs; wherein a first portion of material from each of the holes is included in the corresponding one of the flow deflectors of the first plurality of flow deflectors; and wherein a second portion of material from each of the holes is included in the corresponding one of the flow deflectors of the second plurality of flow deflectors.
 11. The flow device of claim 10, wherein each of the flow deflectors includes compound curvature.
 12. The flow device of claim 11, wherein each of the flow deflectors is a scoop-shaped flow deflector.
 13. The flow device of claim 10, wherein the flow deflectors of each flow deflector pair are oppositely disposed about the corresponding hole.
 14. The flow device of claim 10, further comprising a central flow passage extending through the plate, wherein the plurality of holes are positioned around the central flow passage.
 15. The flow device of claim 14, wherein the plate defines a plurality of notches disposed at a periphery of the plate, the notches extending through the first side and the second side of the plate.
 16. The flow device of claim 15, wherein the holes of the plurality of holes and the notches of the plurality of notches are alternately arranged about a central axis.
 17. An exhaust treatment system comprising: an exhaust conduit for conveying exhaust gases from an engine of a vehicle, the exhaust conduit defining a longitudinal axis; an aftertreatment device disposed in the exhaust conduit; and a flow device disposed upstream of the aftertreatment device, the flow device comprising: a plate having an upstream side and an oppositely disposed downstream side; an opening that extends through the upstream side and the downstream side of the plate; a plurality of first flow deflecting members extending from the upstream side of the plate, each of the first flow deflecting members including a perimeter having a portion that extends around a first portion of the opening; and a plurality of second flow deflecting members extending from the downstream side of the plate, each of the second flow deflecting members including a perimeter having a portion that extends around a second portion of the opening; wherein the first and second flow deflecting members include a first set disposed at a first radial distance from the longitudinal axis and a second set disposed at a second radial distance from the longitudinal axis, and wherein the second radial distance is less than the first radial distance; wherein the opening is one of a plurality of the openings that extends through the upstream side and the downstream side of the plate; and wherein the pluralities of the flow deflecting members are arranged to cause the exhaust gases to swirl about a central axis of the flow device.
 18. The exhaust treatment system of claim 17, wherein: each of the openings has a corresponding one of the first flow deflecting members; and each of the openings also has a corresponding one of the second flow deflecting members.
 19. An exhaust treatment system comprising: an exhaust conduit for conveying exhaust gases from an engine of a vehicle, the exhaust conduit defining a longitudinal axis; an aftertreatment device disposed in the exhaust conduit; and a flow device disposed upstream of the aftertreatment device, the flow device comprising: a plate having an upstream side and an oppositely disposed downstream side; an opening that extends through the upstream side and the downstream side of the plate; a plurality of first flow deflecting members extending from the upstream side of the plate, each of the first flow deflecting members including a perimeter having a portion that extends around a first portion of the opening; and a plurality of second flow deflecting members extending from the downstream side of the plate, each of the second flow deflecting members including a perimeter having a portion that extends around a second portion of the opening, and each of the second flow deflecting members positioned about a second circular arrangement; wherein the first and second flow deflecting members include a first set disposed at a first radial distance from the longitudinal axis about a first circular arrangement and a second set disposed at a second radial distance from the longitudinal axis about a second circular arrangement, and wherein the second radial distance is less than the first radial distance. 